Frequency band allocation device and method

BACKGROUND OF THE INVENTION

p-0002The present invention generally relates to a frequency band allocation device and a frequency band allocation method employed in mobile communications systems in which plural frequency bands are utilized for plural communications systems.

p-0003Nowadays, the technology area for radio communication systems is developing from conventional telecommunications to a variety of schemes such as Bluetooth and radio LAN. For example, a short distance connection such as a several centimeter distance connection was done by a cable in the past, but recently radio connection technology for such short distances has been under development.

p-0004In general, radio communications systems at present, in the same area and same time, employ a single worldwide standard system, such as GSM (Global System for mobile Communications) or IMT-2000 (International Mobile Telecommunication 2000). However, in the future, required communication systems will be diversified depending on their purposes per area and operators. In this situation, plural different systems each of which has a different purpose should be co-mingled in the same time and the same area. For that purpose, mobile stations and base stations should be compatible with these different systems.

p-0005Conventionally, a single radio device can be connected to a dedicated single network. Currently, by having several different kinds of software, a single hardware radio device can be adaptively connected to different networks. Reconfigurable radio devices are also being developed.

p-0006On the other hand, application oriented communications are required. It is tedious for users to select a radio communication route per application, and therefore a radio device is required to automatically select the optimum radio communication route for each application.

p-0007A radio communication device executing different characteristic applications is known, which can select one of plural radio communications systems for each application, based on the application's characteristics, and can determine a frequency band to be used in the selected radio communications system. Such a device is disclosed in Japanese Patent Laid-open Application No.2004-179693.

p-0008However, most part of spectrum has already been allocated to various radio communication systems, and therefore it is difficult to obtain new spectrum for new radio communications systems.

p-0009When new and existing systems have to co-exist during a transition period in the same operator's service, it is required to establish a co-exist control system and method for smoothly transferring from the old system to the new system. In a case where different generation systems co-exist, for example, while a mobile communications system is transferred from the second generation system to the third generation system in the same frequency bands, one frequency band is shared by plural systems. In this case, it is required to establish a control system and method for allowing plural systems to co-exist. It is also required to establish a control system and method for allowing different operators such as public telecommunication operators, broadcasting operators, etc., to co-exist.

p-0010In the future, radio governmental policy regarding frequency band allocation may be changed from the license system in which operators exclusively utilize their licensed frequency bands to the registration system in which any registered operators satisfying certain standards can share and utilize certain frequency bands.

p-0011Frequency bands allocated by the registration system may be utilized by other operators, and therefore it is required to establish an efficient signal transmission system which can avoid interference from and to other systems.

p-0012It is also difficult to obtain a continuous broad bandwidth.

p-0013When a high speed transmission is required, a broad bandwidth is needed, but broad bandwidth is no longer available in spectrum which is suitable for radio communication.

p-0014Since only fragmented frequency bands are available, it is required to establish a multi-band signal transmission technology and an optimum traffic allocation method in order to utilize the fragmented frequency bands. For example, a method for separately allocating frequency bands per each use and a method for controlling resources are required to be established.

p-0015When a user uses one application selected from a variety of applications such as voice, video and data communications, the user side selects a radio system suited for the application within available radio systems. Accordingly it is difficult for operators to allocate radio systems to maximize the frequency utilization factor.

SUMMARY OF THE INVENTION

p-0016An object of the present invention is to provide a frequency band allocation device and a frequency band allocation method in which plural frequency bands can be utilized and transmission information can be allocated differently to an uplink and downlink depending on frequency characteristics.

p-0017The above object of the present invention is achieved by a frequency band allocation device comprising: a frequency band selection unit for selecting usable frequency bands from a dedicated frequency band, a registered frequency band and an unlicensed frequency band: and a frequency band allocation unit for allocating a frequency band out of the selected usable frequency bands to an uplink and downlink, so as to satisfy user required QoS.

p-0018The above object of the present invention is also achieved by a frequency band allocation method comprising the steps of: selecting usable frequency bands based on user information and frequency category information indicating a dedicated frequency band, a registered frequency band or unlicensed frequency band; and allocating to an uplink and downlink, a frequency band satisfying user required QoS out of the selected usable frequency bands.

p-0019According to an embodiment of the present invention, it is possible to realize a frequency band allocation device and a frequency band allocation method employed in mobile communications systems in which plural frequency bands are utilized for plural communications systems.

BRIEF DESCRIPTION OF THE DRAWINGS

p-0020<figref idrefs="DRAWINGS">FIG. 1</figref> is a graph for explaining frequency utilization technology relating to an embodiment of the present invention;

p-0021<figref idrefs="DRAWINGS">FIG. 2</figref> is a block diagram of a communication system according to the embodiment of the present invention;

p-0022<figref idrefs="DRAWINGS">FIG. 3</figref> is a block diagram of a frequency/transmission power allocation device according to the embodiment of the present invention;

p-0023<figref idrefs="DRAWINGS">FIG. 4</figref> schematically shows plural systems co-existing in one area;

p-0024<figref idrefs="DRAWINGS">FIG. 5</figref> is a flowchart illustrating an operational procedure of the communication system according to the embodiment of the present invention; and

p-0025<figref idrefs="DRAWINGS">FIG. 6</figref> is an explanatory view for illustrating frequency selection according to the embodiment of the present invention.

p-0026<figref idrefs="DRAWINGS">FIG. 7</figref> is a flowchart illustrating an operational procedure of the communication system according to the embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

p-0027The following is a description of embodiments of the present invention, with reference to the accompanying drawings.

p-0028Throughout all the figures, members and parts having the same or similar functions are assigned the same or similar reference numerals or symbols, and redundant explanations are omitted.

p-0029A frequency band allocation device according to embodiments of the present invention is explained below with reference to <figref idrefs="DRAWINGS">FIGS. 1 and 2</figref>.

p-0030First, frequency usage technology is explained with reference to <figref idrefs="DRAWINGS">FIG. 1</figref>.

p-0031In a graph shown in <figref idrefs="DRAWINGS">FIG. 1</figref>, the horizontal axis shows frequency and the vertical axis shows frequency utilization factor or frequency efficiency.

p-0032In this case, frequency bands indicated by (<b>1</b>)˜(<b>4</b>) have been already allocated to existing systems. When a new system is started, all the remaining frequency band capacity is allocated to the new system to maximize the frequency utilization factor.

p-0033The frequency band allocation is done by the following schemes. The same frequency band is allocated to and shared by the existing systems and the new system; plural frequency bands are used in one system; and one frequency band is shared by plural new systems.

p-0034Under the situation where frequency bands utilized by one communication service operator and frequency bands utilized by another communication service operator co-exist co-mingled, the frequency band allocation device according to the embodiments of the present invention adaptively controls and utilizes all the remaining open frequency bands to maximize the frequency utilization factor by employing interference recognition technology, frequency sharing technology, interference cancellation technology, interference canceling technology and multi-band control technology.

p-0035Next, a communication system <b>100</b> according to this embodiment is explained with reference to <figref idrefs="DRAWINGS">FIG. 2</figref>.

p-0036The communication system <b>100</b> is placed in, for example, a mobile station or a base station or both. The communication system <b>100</b> comprises an application execution device <b>101</b>, a transmitting device <b>102</b> coupled to the application execution device <b>101</b>, and a control device <b>105</b> coupled to the transmitting device <b>102</b>.

p-0037The transmitting device <b>102</b> comprises a base band signal processor <b>103</b> coupled to the application execution device <b>101</b> and a multi-band RF unit <b>104</b> coupled to the base band signal processor <b>103</b>.

p-0038The control device <b>105</b> comprises a frequency/transmission power allocation unit <b>106</b>, an RF environment recognition unit <b>107</b> coupled to the frequency/transmission power allocation unit <b>106</b>, a user required QoS determination unit <b>108</b>, a transmission parameter determination unit <b>111</b>, an instantaneous RF variation measurement unit <b>109</b>, an RF usage DB <b>112</b>, a user DB <b>113</b>, and a multi-user scheduling control unit <b>110</b> coupled to the base band signal processor <b>103</b>. The transmission parameter determination unit <b>111</b> is connected to the base band signal processor <b>103</b>, and the user required QoS determination unit <b>108</b> is connected to the application execution device <b>101</b>.

p-0039The frequency/transmission power allocation unit <b>106</b>, the RF usage DB <b>112</b> and the user DB <b>113</b> constitute the frequency band allocation device.

p-0040When two mobile stations start communications with each other, or a mobile station starts communications with a server, the application execution device <b>101</b> of the communication system <b>100</b> sends a transmission request to the other mobile station or the server.

p-0041The application execution device <b>101</b> includes a variety of applications and executes these applications to perform voice communication, video communication and data transmission, etc.

p-0042Upon receiving data transmitted through a network from the mobile station or the server to communicate with, the base station inputs the data to the base band signal processor <b>103</b>.

p-0043The mobile station executes a predetermined application among applications stored in the communication system, and inputs digitized transmission data to the base band signal processor <b>103</b>.

p-0044The base band signal processor <b>103</b> in each of the base station and the mobile station selects a transmitting frequency and time per user (multi-scheduling). Depending on RF transmission condition of the used frequency and time, adequate error correction, interleaving, modulation and transmission power are selected as parameters. Input data are transformed to base band signals using these selected parameters, and input to the multi-band RF unit <b>104</b>. The multi-band RF unit <b>104</b> transforms the input base band signals to plural frequency band RF signals, and the transformed signals are transmitted and received.

p-0045The control device <b>105</b> is explained below.

p-0046The frequency/transmission power allocation unit <b>106</b> allocates one or more frequency bands and transmission power levels to each user. It is possible to allocate different frequency bands to uplink and downlink, or allocate different frequency bands to control signals and data signals.

p-0047The RF environment recognition unit <b>107</b> recognizes the current status of frequencies that can be used by each user. For example, at least one item is detected among utilizable frequency bands and bandwidths out of available frequency bands, parameters of other systems utilizing frequencies usable by each user, interference from other systems, transmission loss and shadowing, etc.

p-0048The user required QoS determination unit <b>108</b> determines at least one necessary item per application, among an average transmission data rate, a delay (average delay, maximum delay jitter, etc.), a frame error rate, a transmission power level, the maximum transmission data rate and the minimum guaranteed transmission data rate. These QoS information items are input from the application execution device <b>101</b>.

p-0049In this embodiment, QoS includes an average transmission data rate, a delay (average delay, maximum delay jitter, etc.), a frame error rate, a transmission power level, the maximum transmission data rate and the minimum guaranteed transmission data rate.

p-0050The instantaneous RF variation measurement unit <b>109</b> measures instantaneous variations of the desired signal and interference signals due to fading in frequency and time, in the used channel.

p-0051The multi-user scheduling control unit <b>110</b> performs scheduling for multi-users. The scheduling is performed in both dimensions of frequency and time.

p-0052The transmission parameter determination unit <b>111</b> determines parameters, which are used in the base band processor <b>103</b> for transforming user data to transmission series. More specifically, parameters relating to coding rate, interleaving, modulation transmission power control method, etc., are determined.

p-0053The RF usage DB (data base) <b>112</b> stores categories of frequencies; more specifically, frequency bands (dedicated frequency bands) allocated to each mobile communication service operator, frequency bands (registered frequency bands) that can be utilized by plural registered operators, and frequency bands (unlicensed frequency bands) that can be utilized by anyone satisfying legal conditions. For example, information on frequency category indicating ISM (Industry Science Medical) bands is stored in the RF usage DB <b>112</b>. As for the registered frequency bands and unlicensed frequency bands, the requirements in using the frequency bands such as transmission power limitations are also stored in the RF usage DB <b>112</b>.

p-0054The user DB (data base) <b>113</b> stores categories of users, for example information on usage priority, for example, plans for use for each frequency band, transmission capability, transmission power limitations, signal processing capability, usable RF of mobile stations, etc.

p-0055The frequency/transmission power allocation unit <b>106</b> is explained below with reference to <figref idrefs="DRAWINGS">FIG. 3</figref>.

p-0056The frequency/transmission power allocation unit <b>106</b> comprises an area/time/frequency band selection unit <b>1161</b> coupled to the RF usage DB <b>112</b>, a user's frequency band selection unit <b>1162</b> coupled to the area/time/frequency band selection unit <b>1161</b>, the RF environment recognition unit <b>107</b>, and the user DB <b>113</b>. The frequency/transmission power allocation unit <b>106</b> further comprises a frequency band/transmission power allocation unit <b>1163</b> coupled to the user's frequency band selection unit <b>1162</b>, the RF environment recognition unit <b>107</b> and the user required QoS determination unit <b>108</b>. The area/time/frequency band selection unit <b>1161</b> and the user's frequency band selection unit <b>1162</b> constitute a frequency band selection unit.

p-0057Last, the area/time/frequency band selection unit <b>1161</b> reads category information of frequency bands from the RF usage DB <b>112</b>, and out of the read category information of frequency bands, selects frequency bands that can be utilized by the service operators in the area and time.

p-0058Frequency bands are classified into three categories, that is, dedicated frequency bands, registered frequency bands and unlicensed frequency bands. From the RF usage DB <b>112</b> storing the category information of frequency bands, user utilizable frequency bands are selected.

p-0059For example, the registered frequency bands can be utilized for a variety of services by plural service operators. Therefore, the registered frequency bands can be efficiently used by avoiding interference in area and time to improve the frequency utilization factor.

p-0060For example, frequency bands used for broadcasting are used in some areas but not used in other areas, and not used late at night while the broadcasting is not on-air. Therefore such frequency bands used for broadcasting have much different utilization factors from area to area, and from time to time. Then communication service operators can utilize such broadcasting frequency bands while avoiding interference to the broadcasting to make effective use of the frequency resources.

p-0061As shown in <figref idrefs="DRAWINGS">FIG. 4(</figref><i>a</i>), in an area a where frequency bands f<b>1</b>, f<b>3</b> and f<b>4</b> are utilized for broadcasting, a frequency band f<b>2</b> can be utilized for mobile communication. On the other hand, in an area b shown in <figref idrefs="DRAWINGS">FIG. 4(</figref><i>b</i>), since frequency bands f<b>2</b>, f<b>3</b> and f<b>4</b> are utilized for broadcasting, a frequency band f<b>1</b> can be utilized for mobile communication. In this manner, frequency bands can be adaptively selected and utilized to make efficient use of the frequency resources.

p-0062Frequency bands which are normally not utilized but reserved for very important systems such as disaster control radio communications can also be utilized by having a mechanism for avoiding the existing important systems.

p-0063The area/time/frequency band selection unit <b>1161</b> inputs information on the selected frequency bands to the user's frequency band selection unit <b>1162</b>.

p-0064The user's frequency band selection unit <b>1162</b> reads user information such as user category information and transmission capability information, and based on the read user information, selects frequency bands utilizable by the user among the input frequency bands.

p-0065In ubiquitous communications, there are a variety of mobile terminals, and their performance levels and capabilities are not identical. For example, mobile terminals with high processing capability can perform signal processing over broad radio areas. mobile terminals having large battery capacitance can make transmission power strong, and may have high performance radio circuits and utilize different radio frequencies at the same time.

p-0066On the other hand, a small mobile station with low processing capability such as a sensor, has a low signal processing capability, and therefore cannot accommodate broadband signals. Such a small mobile station has a small battery capacity and therefore has a small transmission power level and a limited scale of radio circuit, and further usable RF is limited due to antenna and radio circuit limitation. Based on this kind of information, usable frequency band selection is further limited.

p-0067In the registered frequency bands and the unlicensed frequency bands, their communication environments may be degraded due to interference by other operators. Therefore, the user's frequency band selection unit <b>1162</b> allocates these frequency bands to best effort applications or low priority users such as users having cheap plans of use. The “best effort” means allocating to mobile stations the maximum transmission data rate which can be made available at present. The user's frequency band selection unit <b>1162</b> allocates dedicated frequency bands to real time application users such as voice, video or high priority users such as users having an expensive plan of use.

p-0068The user's frequency band selection unit <b>1162</b> inputs selected frequency band information to the frequency band/transmission power allocation unit <b>1163</b> and inputs them also to the RF environment recognition unit <b>107</b>.

p-0069The RF environment recognition unit <b>107</b> detects control signals or reception power in the input frequency band information, and detects the current status of each frequency band. More specifically, the RF environment recognition unit <b>107</b> collects information on utilizable frequency bands and bandwidths among frequencies available to each user, parameters of other systems utilizing frequencies usable by each user, interference level from own system to other systems, interference levels from other systems, required transmission power level, transmission loss and shadowing. The RF environment recognition unit <b>107</b> inputs the collected RF environment condition to the frequency band/transmission power allocation unit <b>1163</b>.

p-0070On the other hand, the application execution device <b>101</b> inputs QoS information per application to the user required QoS determination unit <b>108</b>. The user required QoS determination unit <b>108</b>, based on the input QoS, determines at least one necessary item per application, among an average transmission data rate, a delay (average delay, maximum delay jitter, etc.), a frame error rate, a transmission power level, the maximum transmission data rate, and the minimum guaranteed transmission data rate. The user required QoS determination unit <b>108</b> inputs the determined item to the frequency band/transmission power allocation unit <b>1163</b>.

p-0071Real time communications have a small tolerance against delay, which may be accepted by some applications. For example, in a voice communication system, when an error is detected, muting is carried out to prevent the user from noticing the quality degradation, and therefore certain level of frame error can be accepted.

p-0072On the other hand, in data transmission, since delay is acceptable to some extent, frame error rate can be reduced to wired communication level by performing retransmission control.

p-0073The frequency band/transmission power allocation unit <b>1163</b>, based on the status of utilizable frequency bands sent from the RF environment recognition unit <b>107</b> and the QoS determination information sent from the user required QoS determination unit <b>108</b>, selects frequency bands and bandwidths to be allocated to each user, and calculates required average transmission power. For example based on transmission characteristics or available bandwidths of used plural frequency bands, allocation is done so as to satisfy a variety of required QoSs from high rate to low rate.

p-0074Frequency characteristics are explained.

p-0075High frequency bands give broadband allocation, but have large transmission loss. Therefore, when utilizing them for uplink, it is required to have large transmission power level for mobile terminals, resulting in usable area becomes smaller. On the other hand, low frequency bands give narrowband allocation, but have small transmission loss. Therefore, it is possible to have stable communication even without large transmission power.

p-0076The frequency band/transmission power allocation unit <b>1163</b> selects a frequency band(s) while satisfying user required QoS (transmission data rate, delay, error rate) and the maximum allowable transmission power by the terminal, and maximizes the frequency utilization factor over the whole system and further maximizes the service coverage area with the acceptable transmission power.

p-0077As for dedicated frequency bands that can be controlled by owning service operators, their transmission power is calculated based on service operator's acceptable interference power. As for registered frequency bands that can only be used by registered service operators, their transmission power is calculated in accordance with interference avoidance rules defined among the service operators. As for unlicensed frequency bands that can be utilized by anyone, legally stipulated transmission power is utilized.

p-0078For example, the frequency band/transmission power allocation unit <b>1163</b>, based on the interference reception power sent from the RF environment recognition unit <b>107</b>, calculates necessary transmission power for each user.

p-0079Based on the QoS information input from the user required QoS determination unit <b>108</b> that is QoS required by the user, the frequency band/transmission power allocation unit <b>1163</b> allocates low frequencies to distant users or users wanting a wide service area, and allocates high frequencies to users wanting high speed transmission or broadband transmission.

p-0080Here, where there is no continuous frequency band satisfying user's required bandwidth, it is possible to select and allocate plural utilizable frequency bands to one user. If there are plural frequency bands satisfying requirements, allocation can be done so as to spread frequency loads estimating traffic condition. Frequency bands can be allocated so as to minimize transmission power level in order to reduce interference and improve frequency utilization factor. Frequency bands can be allocated so that transmission power level satisfies a predetermined value.

p-0081Since the RF environment varies continuously, the selected frequency band can be altered depending on the change of the environment. Therefore, it is possible to periodically select frequency bands or select frequency bands per call or packet.

p-0082The frequency band/transmission power allocation unit <b>1163</b> can select different frequency bands for uplink and downlink. In some applications such as data transmission, downlink traffic from a server may be multiple times larger than uplink traffic to the server. Data information amount becomes several times or several dozen times larger than control information amount for maintaining communication.

p-0083In best effort type data communication, delay demand is not so strict than real time communication. Therefore, enough throughputs can be attained even via erroneous communication route by performing retransmission control. However, if feedback information used for retransmission has errors, delay is increased and throughputs are degraded.

p-0084In this case, by selecting asymmetric bandwidths for an uplink and downlink, asymmetric traffic can be efficiently accommodated.

p-0085Some mobile stations have small available transmission power. In this case, by allocating a low frequency band having small transmission loss to its uplink, it is possible to keep low power consumption of the mobile terminal while maintaining an available broad service area.

p-0086The control information includes information necessary for maintaining communication and feedback information for retransmission. Therefore, if transmission error occurs, it is impossible for a receiver side to recover data even without data information error. Accordingly, it is required to minimize transmission error.

p-0087The frequency band/transmission power allocation unit <b>1163</b> can select different frequency bands for uplink and downlink. In some applications such as data transmission, downlink traffic from a server may be multiple times larger than uplink traffic to the server. In this case, such asymmetric traffic can be efficiently accommodated by selecting asymmetric frequency bandwidths.

p-0088For example, in a case where broadband high frequency and narrowband low frequency can be utilized at the same time, uplink and downlink control channels and uplink data channel are allocated to the narrowband low frequency band and downlink data channel is allocated to the broadband high frequency band. In this manner, it is possible to increase the downlink transmission capability with maintaining wide coverage area.

p-0089The information such as thus selected frequency bands, bandwidths and transmission power level is input to the transmission parameter determination unit <b>111</b>. For example, as for data signals and control signals, the information such as the selected frequency bands, bandwidths and transmission power is input to the transmission parameter determination unit <b>111</b>.

p-0090The transmission parameter determination unit <b>111</b>, based on the input information such as the used frequency band, bandwidth and transmission power, determines parameters used in the base band signal processor <b>103</b> transforming the transmission data to transmission series, and inputs the determined parameters to the base band signal processor <b>103</b>.

p-0091The base band signal processor <b>103</b> uses the input parameter and performs error correction coding, interleaving, modulation, transmission power control, multi-user scheduling per user, and inputs plural frequency band signals to the multi-band RF unit <b>104</b>. For example, the multi-user scheduling is performed in dimensions of both frequency and time. When the scheduling is done in the frequency dimension, the allocated frequencies that are apart from each other can be controlled separately, and the allocated frequencies that are close to each other can be controlled together.

p-0092The multi-band RF unit <b>104</b> uses the allocated frequency bands to transmit data. For example, one RF unit having a software radio function can be utilized by changing parameters for each frequency or different subunits are prepared and used by switching for different frequency bands.

p-0093Next, the operation of the communication system <b>100</b> according to this embodiment is explained with reference to <figref idrefs="DRAWINGS">FIG. 5</figref>.

p-0094At first, frequency category information is read from the RF usage data base <b>112</b> at step S<b>502</b>.

p-0095Based on the read frequency category information, it is determined whether the service operator can select frequency bands that can be used in the area and time at step S<b>504</b>. If available frequency bands can be selected (YES at step S<b>504</b>), frequency bands are selected at step S<b>506</b>. On the other hand, if available frequency bands cannot be selected (NO at step S<b>504</b>), the procedure goes to callo blocking for voice communication or packet loss for data transmission at step S<b>518</b>.

p-0096For example, the RF usage database <b>112</b> stores frequency category information such as dedicated frequency bands, registered frequency bands and unlicensed frequency bands shown in <figref idrefs="DRAWINGS">FIG. 6(</figref><i>a</i>). After reading the frequency category information, the area/time/frequency band selection unit <b>1161</b> selects frequency bands that can be used in the area and time. For example, 300 MHz band, 800 MHz band, 2 GHz band and 5 GHz band shown in <figref idrefs="DRAWINGS">FIG. 6(</figref><i>b</i>) are selected as available frequency bands.

p-0097Next, user information is read from the user database <b>113</b> at step S<b>508</b>. Based on the read user category information, it is determined at step S<b>510</b> whether it is possible to select utilizable frequency bands out of the frequency bands selected at step S<b>506</b>.

p-0098If it is possible to select utilizable frequency bands (YES at step <b>510</b>), utilizable frequency bands are selected at step S<b>512</b>. On the other hand, it is impossible to select utilizable frequency bands (NO at step S<b>510</b>), the procedure goes to call blocking for voice communication or packet loss for data transmission at step S<b>518</b>.

p-0099For example, the user's frequency band selection unit <b>1162</b> selects frequency bands the same as the input frequency band candidates as shown in <figref idrefs="DRAWINGS">FIG. 6(</figref><i>c</i>).

p-0100Based on at least one item of usable channels, available bandwidths and parameters of other system utilizing usable frequency bands, interference from other system, transmission loss and shadowing input from the RF environment recognition unit <b>107</b>, or based on at least one item of an average transmission data rate, delay information, a frame error rate transmission power level, the maximum transmission data rate, and the lowest guaranteed transmission data rate that are necessary per application and input from the user required QoS determination unit <b>108</b>, it is determined whether the frequency band/transmission power allocation unit <b>1163</b> can select frequency bands/transmission power levels to be used per user at step S<b>514</b>. If it is possible to select utilizable frequency bands/transmission power levels (YES at step S<b>514</b>), frequency bands, bandwidths and transmission power levels are determined and the frequency bands are allocated at step S<b>516</b>.

p-0101For example, as shown in <figref idrefs="DRAWINGS">FIG. 6(</figref><i>d</i>), the 300 MHz band, 800 MHz band, 2 GHz band and 5 GHz band are allocated. If there is no continuous frequency band having a bandwidth satisfying user's request, it is possible to allocate plural utilizable frequency bandwidths to one user. Different frequencies can be allocated to data signals and controls signals. On the other hand, if it is impossible to select frequency band/transmission power level to be used (NO at step S<b>514</b>), the procedure goes to callo blocking for voice communication or packet loss for data transmission at step S<b>518</b>.

p-0102Next, a frequency band allocation procedure performed in the frequency band/transmission power allocation unit <b>1163</b> is explained with reference to <figref idrefs="DRAWINGS">FIG. 7</figref>.

p-0103At first, in response to user's connection request, surrounding RF utilization status input from the RF environment recognition unit <b>107</b> is recognized, and utilizable frequency bands are searched among frequency bands available to his mobile terminal to determine candidates for frequency bands and bandwidths to be utilized at step S<b>702</b>.

p-0104Next, transmission rate (requested by the user) input from the user required QoS determination unit <b>108</b> and available frequency bandwidths are compared, and allocatable bandwidth candidates are selected among the candidates for frequency bands and bandwidths at step S<b>704</b>.

p-0105A necessary SIR is estimated at step S<b>706</b>, and it is determine whether frequency band satisfying required transmission rate, error rate and required transmission power upper limit exists at step S<b>708</b>.

p-0106If a frequency band satisfying the requirements exists (YES at step S<b>708</b>), then it is determined whether plural frequency bands satisfying the requirements exist at step S<b>710</b>. On the other hand, no frequency satisfying the requirements exists (NO at step S<b>708</b>), plural frequency bands are multiplexed and allocated so that one user can utilize them at the same time at step S<b>712</b>.

p-0107At step S<b>710</b>, if plural frequency bands satisfying the requirements exist (YES at step S<b>710</b>), traffic status is estimated at step S<b>714</b> and frequency bands are allocated so as to spread frequency loads at step S<b>716</b>.

p-0108In order to improve frequency utilization factor by reducing interference, it is possible to select frequency bans so as to minimize transmission power level.

p-0109On the other hand, only one frequency band satisfying the requirements (NO at step S<b>710</b>), the frequency band is allocated at step S<b>718</b>.

p-0110According to this embodiment of the present invention, since service operators can utilize dedicated plural frequency bands other than already allocated frequencies, it is possible to flexibly deal with heavy traffic occurrence with uneven time distribution and uneven area distribution. It is also possible to allocate plural frequency bands to one system.

p-0111It is possible to satisfy user required QoS, maximize the frequency utilization factor over the whole system and keep power consumption low while maintaining a wide service area, and therefore realize mobile terminals that can be used in any area.

p-0112Since the control channel is transmitted without error, it is possible minimize overhead such as necessary transmission power and channel coding and provide stable data communication with maintaining wide coverage area.

p-0113In a communications system in which plural frequency bands can be utilized, a variety of mobile terminals can be accommodated while satisfying a variety of QoSs (such as transmission rate, error rate, etc.), which are different depending on different frequency characteristics, users, an uplink and downlink.

p-0114Different frequency bands can be allocated to an uplink and downlink, with considering the asymmetry of the uplink and downlink, and transmission power requirement conditions of mobile stations and base stations.

h-0005[Industrial Applicability]

p-0115A frequency band allocation device and a frequency band allocation method according to the present invention can be utilized in mobile communications systems in which usable frequency bands are utilized for plural communications systems.

p-0116The present application is based on Japanese Priority Application No. 2004-275586 filed on Sep. 22, 2004 with the Japanese Patent Office, the entire contents of which are hereby incorporated by reference.